#!/usr/bin/env python3
"""A small CLI that prints a customizable greeting."""

import argparse
import unittest
from collections.abc import Sequence


def build_parser() -> argparse.ArgumentParser:
    """Create the command-line argument parser."""
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("name", nargs="?", default="World", help="name to greet")
    parser.add_argument("-n", "--count", type=int, default=1, help="number of greetings")
    parser.add_argument("--uppercase", action="store_true", help="use uppercase output")
    parser.add_argument("--test", action="store_true", help="run the built-in tests")
    return parser


def make_greeting(name: str, uppercase: bool = False) -> str:
    """Return a greeting for the supplied name."""
    greeting = f"Hello, {name}!"
    return greeting.upper() if uppercase else greeting


class GreetingTests(unittest.TestCase):
    def test_default_greeting(self) -> None:
        self.assertEqual(make_greeting("Ada"), "Hello, Ada!")

    def test_uppercase_greeting(self) -> None:
        self.assertEqual(make_greeting("Ada", uppercase=True), "HELLO, ADA!")


def main(argv: Sequence[str] | None = None) -> int:
    """Parse arguments and run the CLI."""
    args = build_parser().parse_args(argv)

    if args.test:
        suite = unittest.defaultTestLoader.loadTestsFromTestCase(GreetingTests)
        return 0 if unittest.TextTestRunner().run(suite).wasSuccessful() else 1

    if args.count < 1:
        build_parser().error("--count must be at least 1")

    greeting = make_greeting(args.name, args.uppercase)
    for _ in range(args.count):
        print(greeting)

    return 0


if __name__ == "__main__":
    raise SystemExit(main())